1. Field of the Invention
The present invention relates to a magnetic recording medium that is suitable for recording information using a heat-assisted magnetic recording method.
2. Background Art
Recently, a magnetic recording medium (hereinafter, referred to as a disk) such as a hard disk in a computer device requires a new high density in response to a need to perform the recording and playback of high capacity and high-density information or the like. For that reason, in order to suppress influence between adjacent magnetic domains or thermal fluctuations to the minimum, a medium having strong coercive force has begun to be adopted as the disk. For that reason, it is difficult to record information on the disk.
Thus, in order to solve the disadvantage mentioned above, a writing method using a heat-assisted magnetic recording method (a hybrid magnetic recording method) is provided in which the magnetic domain is locally heated using a spot light with a focused light or a near-field light to temporarily lower the coercive force, thereby performing the writing onto the disk in the meanwhile.
Particularly, in the case of using the near-field light, it is possible to handle optical information in a region equal to or less than a wavelength of light to which an optical system of the related art is limited, and it is possible to promote increased density of recording bits unobtainable in the past.
Incidentally, many disks corresponding to the heat-assisted magnetic recording method mentioned above are now provided, but in such disks, there is a need for effective heating of a magnetic body (a magnetic cluster constituted by one or plurality of magnetic particles) constituting a recording layer as one of the requirements for reliably performing the heat-assisted magnetic recording.
This is because rapidly heating a desired magnetic body to lower the coercive force leads to a suppression of recording defects and reliability of writing.
Thus, a magnetic recording medium is known in which a highly thermal conductive thin film having a thermal conductivity higher than that of the recording layer is disposed on an upper portion and a side portion of a recording track (the magnetic body) constituting the recording layer (for example, see JP-A-2010-165404). According to the magnetic recording medium, it is possible to transmit heat from the outside of the recording track by the highly thermal conductive thin film, which is able to rapidly heat the entire recording track.
However, in the magnetic recording medium disclosed in JP-A-2010-165404, since the highly thermal conductive thin film is disposed in a state of coming into contact with the upper portion and the side portion of the recording track, a part of the heat transmitted to the highly thermal conductive thin film during heating easily escapes in a direction different from that of the recording track. For that reason, it is difficult to transmit the heat from the highly thermal conductive thin film side to the recording track side without waste, whereby the recording track is not effectively heated.
Furthermore, there is also a concern that heat not contributing to the heating of the recording track and escaping in the direction different from the recording track being transmitted to other recording tracks via the adjacent highly thermal conductive thin film may happen. For that reason, there is also a possibility of heat lowering the thermal stability of the other recording tracks, information recorded on the recording track in advance being lost and information being erroneously recorded.